In the design of traverse rods for the support of especially heavy curtains a number of problems arise. For example, the usual C-shaped cross-sectioned telescoping rod although satisfactory for light curtains, is not well suited for the support of heavy curtains due to the eccentric application of the weight of the curtain to the lower lip of the C at the rear face of the rod. This introduces undesireable torsion in the rod between the supports. A preferred cross-section for heavy duty rods, therefore, comprises an inverted U-shape having a slot in its lower face defining one or two tracks on which the curtain carriers ride. In this way the weight of the curtain can be applied more nearly along the centerline of the rod and torsion is minimized. The inverted U-shape, however, has other disadvantages. Thus, with the C-shape, the draw cord remains within the lower semi-circle of the C and has no tendency to come out of the slot in the back of the rod, whereas, with an inverted U-shape, the cord tends to drop out of the slot and otherwise to interfere with the action of the carriers. In addition, with the C-shape it is relatively easy to lead a bight of the draw cord out of the rod to the rear of the master carriers, so that, simply by looping the bight over an exposed hook or cleat on the rear face of the master carrier the position of the master carrier, along the rod, can be adjusted and fixed. However, with the inverted U-shaped cross-section a bight of cord extending below the rod would be undesireable and unsightly.
Still another problem has to do with the spacial relationship between the support points for the curtain. Usually, master carriers are elongated and slide on two contact points spaced longitudinally of the rod. The reason for the longitudinal spacing of the support points for the master carriers is that, in order to avoid jamming, the master carrier needs to be supported against longitudinal tipping while it is being pulled along the rod by the draw cord. In addition, in many designs the master carrier is provided with an extension arm in order to support the curtain edges in overlapping relation, and the master carrier needs to be elongated in order to support the extension arm. The elongation of the master carrier, however, makes it impossible for the support points of the idler carrier to be moved to a position adjacent to the support points of the masters. This prevents the portion of the curtain which is supported by the master carrier from coming together when the curtain is pulled to the fully opened position, and leaves an unpleated portion at the edge of the curtain. The effect is particularly noticeable with woven wood type curtains which come together in accordian fashion. If the slats cannot come together with all support points equally spaced, the symmetry of appearance is lost.
Other problems associated with supporting heavy weight curtains have to do with improving the ease of longitudinal motion of the carriers on the tracks of the rod and a reduction of interference between the carriers and the ends of the telescoping rod sections within the rod.
The general object of the present invention, therefore, is to provide a curtain rod and support combination adapted to support heavy weight curtains for free rolling, virtually friction-free action within the rod. Still another object is to provide a telescoping rod and support combination equipped both for free rolling action and for transition of the curtain supporting elements from one telescoping section to another without interference from the ends of either section. Another object is to provide a master carrier for such a combination which extends longitudinally within the rod, but which at the same time permits the idler carriers to overlap the master so that, when the curtain is fully opened the support points for the curtain may be equally spaced at the side of the window frame. Still another object is to provide a master carrier and draw cord arrangement for a telescoping rod having an inverted U-shaped cross-section, which cord and master carrier arrangement permits the cord to remain within the rod without risk of dropping out of the opening in the bottom of the rod and which also permits proper positioning of the master relative to the rod for any selected rod length followed by fixing the master carrier in that position without a visible protrusion of a bight of cord below the rod.